Process of evaporating moisture from syrup-forming solutions



Jan. 7, 1958 D. B. VINCENT 2,318,917

- PROCESS OF EVAPORATING MOISTURE FROM SYRUP-FORMING SOLUTIONS OriginalFiled June 27, 1949 4 Sheets-Sheet 1 DI/V/EL B. W/VCENT mmvroa.

Jan. 7, 1958 0. B. VINCENT 2,313,917

PROCESS 'OF EVAPORATING MOISTURE FROM SYRUP-FORMING SQLUTIONS OriginalFiled June 27, 1949 4 Sheets-Sheet 2 00ML B. lJ/VCENT INVENTOR.

Arm/mas Jan. 7, 1958 D. B. VINCENT PROCESS OF EVAPORATING MOISTURE FROMSYRUP-FORMING SOLUTIONS Original Filed June 27, 1949 4 Sheets-Sheet 3INVENTORL a) a I 06w 4 TTORNE Y5 Jan. 7, 1958 D. B. VINCENT PROCESS OFEVAPORATING MOISTURE FROM SYRUP-FORMING SOLUTIONS Original Filed June27, 1949 4 Shea 1.s-Sheet 4 PROCESS OF EVAPGRATING MOISTURE FROMSYRUP-FORMING SOLUTIONS Daniel B. Vincent, Tampa, Fla, assignor toPrentice E. Edrington, Washington, D. C.

13 Claims. (Cl. 159-43) This invention relates to a process, operatingunder atmospheric pressure conditions, for evaporating moisture fromsolutions and/or suspensions of materials which when concentrated tendto form syrupy gel-like, or sticky concentrates of substances whichdecompose when heated. This application is a division of my co-pendingapplication, Serial No. 101,662, filed June 27, 1949, now Patent No.2,684,713, issued July 27, 1954.

Applicant and others associated with him have been engaged in thedevelopment of apparatus and. processes for concentrating materials suchas citrus by-products to make citrus syrups and citrus molassestherefrom, for the production of useful gel-like and viscousconcentrates obtained from the residue known as fish stick produced inthe menhaden and related fishing industries, and for the concentrationof wash waters obtained in the paper pulp and wall board industry all ofwhich present diflicult problems in the conventional heat exchanger orindirect heat type evaporator. These substances tend to precipitatesticky fractions during evaporation caused by breaking down or charringof the soluble portions and by the high percentage of insolubleparticles which adhere to the tubes of the evaporator and progressivelybuild up a scale which slows down and finally inhibits heat transfer.This difiiculty usually occurs in the first effect where the steamtemperature is in the range approximately 250 F. and the liquidtemperature about 225 F. In the case of citrus molasses these steam tubeevaporators must be drained of molasses every 72 hours and boiled outwith caustic soda for 6 hours. Wood pulp Wash waters give endlesstrouble and it is necessary to drain and clean the steam tubeevaporators every day and once weekly to bore out the choked tubes witha special tool. In the fish industry the press liquors known as stickwaters glue up the tube surfaces and frequently break down and spoil andbecome unfit for the market.

These products are usually high in moisture content, for example; citruspress waters average about 91 percent water, fish stick 94 percent waterand wood wash waters from 93 to 96 percent water, and in many cases thefinished product must be sold at a low price or even burned as fuel toprevent stream pollution. Fuel necessary for evaporating the water andthe time required for draining and cleaning the equipment are thereforeimportant factors in these fields. The foregoing substances areillustrative of fairly numerous types of solutions in which the crudesolution contains appreciable quantities of water and less quantities ofsoluble and suspended matter, many of which possess much more value inconcentrated form. Both in the illustrative types of solutions and inother related types of solutions, the crude or raw stock material is arelatively dilute solution which may contain oleaginous (i. e. fishoils) or non-oleaginous organic matter, in true solution, or insuspension or in the form of emulsions, and mixtures of the same.

All of these substances contain water soluble solids in solution andwater insoluble solids in suspension which can be diluted and easilywashed from metal surfaces if the metal surfaces are cooler than or notmuch hotter than the liquids containing the solids. Therefore if theevaporator is constructed and the processing conducted so that this isaccomplished and if the liquids being concentrated are circulated'inlarge quantities over the metal surfaces of the evaporator to keep themthoroughly washed and cleaned no sticking of the material beingconcentrated can occur and no shut down for cleaning the equipment isever necessary. Also the suspended solids and concentratingliquidsbecome thoroughly homogenized due to the rapid and constantmixing action of the pumps and fans during the recycle period. The finalconcentrate is therefore of better quality than other types aspractically no solids precipitate during storage.

Therefore one object of this invention is. to process materials of theindicated type in a manner such as to utilize the high etficiency ofdirect contact for heat transfer between a liquid and a gas.

Another object is to process such materials in a manner such that theliquid concentrating device in which the processing is performed iscontinuously self cleaning.

The present invention also has for one of its objects the control ofevaporating conditions and the carrying out of the evaporating of theundesired moisture under such conditions that moisture is efficientlyand quickly removed while the concentrate is obtained without raisingthe temperature of the decomposable materials to temperatures 'much'in'excess of F., even though the system is maintained under atmosphericpressure and materials being concentrated are subjected to direct heatof heating gases which may be as hot as l400 F. to 1900 l Another objectof 'the present invention is the carrylog out of the herein describedprocess in such a manner as to avoid permitting the concentrating orconcentrated materials from collecting at any stage or treatment whereinthey would be subject to overheating with attendant decomposition,charting, or caramelization.

A further object of the present invention. is to process materials ofthe indicated type so as to permit a rapid partial concentration of theraw material to produce, efliciently and continuously a partiallyfinished, or partially concentrated product which may then be subjectedto final. concentration in a vacuum concentrator by use of all or partof the latent energy developed in the first effect, or preferably in asecond effect evaporating system. such as that illustrated in the priorapplication of Charles R. Picker, Serial No. 64,538, filed December 10,1948, now abandoned. It may be observed that the present application isan improvement upon and a continuation in part of applicants priorapplication, Serial No. 632,467, filed December 3, 1945, now abandoned.In said. prior application, Serial No. 632,467, there is illustrated inFigure 1 of the drawings an arrangement of apparatus which is a germanevariation of the disclosure of this application. There is alsodisclosed, in Figure 5 of said application Serial No. 632,467, anarrangement of apparatus in which the concentration of desired productsis performed by passing the raw stock material successively through twogenerally similar evaporating units. It will be understood that thepresent invention contemplates as within its scope the duplication ofthe single illustrated evaporating chamber so as to pass theconcentrating fluids through two or more units in a manner analogous tothe system illustrated in Figure 5 of said prior application, utilizingpart or all of the latent energy generated in the first effect as asource of energy for evaporation in the other effects.

Another object of the present invention is the avoidance of the skilledpersonal supervision required for prior art, multi-stage or batchoperations and the en pense, for equipment and operations, which attendsvacuum processing in conventional vacuum systems.

In its broader aspects, the process of the invention invo liquid. Theprocess may be carried out continuously, closed system, conditions.

In carrying out the process, a stream of highly heated combustion gasesat high velocity and under atmospheric pressure, and a stream of theliquid to be concentrated, are simultaneously introduced into anevaporating zone, In counter-current flow relation along a common axis,

in a and preferably under atmospheric pressure by causing intimateturbulent mixing. The gases and liquid, thoroughly mixed andintermingled, pass outfor use, Herein the movement of rapid, isquiescent as dis- Figure 3 is a detailed side elevational view, somewhatdiagrammatically, of the separating chamber;

Figure 4 is a detail, rear elevation, partly in crosssection of theinterior of the primary evaporating chamber; and

Figure is a flow-sheet which illustrates the steps of the process ascarried out in an illustrative embodiment thereof.

Referring more particularly to Figures I and 2 of the drawings, 1represents generally a furnace or heater which is provided with anexterior casing or jacket 2 within which and spaced from the jacket 2 isa combustion chamber 3 prepared of fire brick or suitable heat resistantmaterial. Within the combustion chamber 3 is a primary combustion zone 4provided at one end thereof with an inlet orifice 5 and at the other endwith a discharge orifice 8. A suitable fuel burner 6 is located exteriorof the furnace 1 and discharges the fuel for combustion through one ormore nozzles 7 which are disposed in spaced relationship from the wallsof the inlet orifice 5. Air necessary to support primary combustion ofthe fuel is introduced through orifice 5 and around fuel nozzles 7.

The hot products of primary combustion leave the combustion zone throughthe discharge orifice 8 and enter a gas mixing chamber 9 where the hotcombustion gases are mixed with desired quantities of auxiliary airwhich enters the furnace from ports 10 and flows through conduits 11between the walls of the exterior jacket 2 and the walls of thecombustion chamber 3. The hot gases, containing desired amounts ofauxiliary air, after mixing in gas chamber 9 pass into a flue 12 andthence upwardly into a cylindrical duct 15.

A suitable auxiliary stack 13 provided with a cut-off valve or damper 14communicates with flue 12 in order to draw off combustion gases asduring periods of shutdown. The cylindrical duct 15 has adjacent itsbottom a damper or valve 16 which in open position permits duct 15 tocommunicate directly with flue 12 but which when moved to a position1611 serves to close off duct 15 and permit the by-passing of combustiongases and their discharge out of the auxiliary stack 13. Desirably, thecylindrical duct 15 will be surrounded by a spaced concentric outerjacket 17 which is open at the bottom to provide an air inlet 18 andwhich is vented at the top, as shown at 19, to permit the discharge ofair. The purpose of this exterior jacket or sleeve 17 is to permitcooling air to be aspirated in the space between the jacket 17 and ductchamber 15 so as to cool the walls of the chamber somewhat and avoidoverheating of the walls, also to form a cooling air cushion between thehigh temperature gases moving through duct 15 and the metal rolled lip22, Figure 4.

The cylindrical duct 15 discharges at its upper end into a primaryevaporating chamber generally designated 20 which is closed at its top,sides, and bottom by a housing. The bottom of the housing 21 has aninclined pitch downwardly and outwardly and terminates at its innerupper ends in an annular lip 22 which extends to a point somewhat aboveand inside of the path of rotation of the bottom inner edges of the fanblades. The bottom 21 of the housing also has a pitch in the generaldirection toward the duct 23 so as to permit fluids which collect in thebottom of the housing to flow by gravity toward and through duct 23.Duct 23 communicates with a somewhat larger duct 24 which travelsgenerally horizontally and terminates tangentially with the housing ofthe primary separating chamber 55.

The raw feed stock or fluid to be concentrated is pumped from a suitablesupply vat, not shown, through an inlet pipe 25 by means of pump 26 anddischarged through pipe 27 into supply vat 28. Vat 2.8 communicates withrecycle vat 30 through a bottom orifice at the base of bafile orpartition 36. Similarly, recycle vat 30 communicates with concentratevat 31 through a bottom orifice at the base of partition 37. The amountof raw stock or feed introduced through pipe 27 is controlled by controlelement 32 which operates in accordance with the liquid level in vat 28responsive to the float 33. Control 32 may function through mechanicalor electrical connections 34 to open and close control valve 35 placedin feed line 27, or alternatively control 32 may have suitableelectrical connections, such as 34 to control the motor or pump 26 forcontinuous or intermittent operation thereof as desired.

A draw-off pipe 38 communicates with the body of liquid in recycle vat39 to withdraw fluid therefrom, and by means of pump 39 pumps thewithdrawn fluid through pipe 40 and thence to a T connection, one arm ofwhich, 411, communicates with the interior of evaporating chamber 20 aswill be further described and the other arm of which, 42, communicateswith the interior of the primary separating chamber 55 as will befurther described. Fluid flowing from pipe 40 through 41 then flowsdownwardly into shaft 45.

Shaft is provided with suitable bearing blocks, gaskets and housings,designated 43 and 44, to permit rotation of shaft 45 around a verticalaxis. Shaft 45 has mounted thereon a pulley 46 connected by belt 47 topulley 48 mounted on the shaft of a suitable motor 49. The lowerextremity of shaft 45 is open to provide a discharge orifice 50. Mountedon the shaft is a suitable gas impeller adapted for rotationsimultaneously with and responsive to rotation of shaft 45. In Figure lof the drawings, the impeller is shown conventionally as having asupporting disc 52 and a plurality of blades or vanes 51. Desirably, theimpeller may be constructed in accordance with the constructionillustrated in Figure 3 of applicants prior application Serial No.632,467, now abandoned, or the fan structure illustrated in Figures 2,3, 4, and 5 of prior application of Charles R. Picker, Serial. No. 173,filed January 2, 1948, and now abandoned, may be employed. Regardless ofwhich specific form of impeller blade structure is employed, it isimportant that the rotating shaft 45 be in axial alignment with thecenter of duct 15 and that the fluid discharge orifice or orifices 50 beplaced just above the center of the gas discharge outlet at the top ofduct 15. This concentric, opposed, relationship appears more clearlyfrom the plan view illustrated in Figure 2 of the drawings. Figure 2 ofthe drawings also illustrates an important feature which is thatdischarge conduit 23 is arranged tangentially with respect to housing20.

The primary separating chamber 55 consists of a generally cylindricalhousing having a side opening therethrough which provides for thetangential introduction of gases which are discharged from chamber 24.Chamber 55 otherwise has its sides fully enclosed, has at the basethereof a conical collecting basin 56 which terminates in a liquiddischarge pipe 57, which, in turn, conveys liquid into concentrate vat31. A center opening is provided at the top of chamber 55 and a somewhatrestricted throat 58 provides :a conduit leading into a gas duct 59. Theliquid pipe 42 referred to above is provided with a suitable controlvalve 53 and terminates in a perforated nozzle which is disposedcentrally of, and preferably toward the bottom of, the restricted throat58; Duct 59 communicates wtih the secondary separating chamber 60 which,in turn, communicates with a gas discharge fine 61. Chamber 60 has acollecting basin 62 which terminates in a conical basin 63 whichdischarges into pipe 64 which conveys fluid to supply vat 28.

Concentrate vat 31 is provided with a drawoff pipe 65 from which theconcentrated product is pumped by pump 66 into a discharge line 67 wherethe concentrate may be stored as a product or for further treatment.Desirably, but not necessarily, flue 61 and product pipe 67 maycommunicate with a second effect concentrating system such as isdisclosed in application Serial No. 64,53 8, now abandoned, filedDecember 10, 1948 by Charles R. Picker.

Referring to Figure 3, which is a somewhat enlarged detailed View of theprimary separating chamber 55, it will be noted that Figure 3 is a rearelevation, while in Figure 1, the same element is shown as a frontelevation. The gases discharged into chamber 55 from duct 24 areintroduced tangentially and under considerable velocity which permitsthe chamber 55 to function as a cyclone separator in which suspendeddroplets of liquid which have been carried along with the gases arethrown outwardly and against the interior walls of chamber 55 where theymay drain downwardly and collect in basin 56. Since the solids presentin these concentrated liquids have appreciable viscosity, it is possiblefor small droplets, ribbons, or streamers of concentrate to be carriedby the gases. Where these particles are sufficiently light, there is atendency for them to be carried upwardly through the throat 58 andthence into the secondary separating chamber. There is also a tendencyfor the concentrated liquids to tend to cling to the interior side wallsof the primary separating chamber 55. To eliminate these two tendenciessome of the less concentrated recycle stock is supplied through nozzle54 and into chamber 55. A conical spray is preferred since in elfect itprovides a liquid bafile which washes the gases as they pass upwardlythrough it, thus removing entrained droplets or ribbons of concentrate.Moreover, since the wash liquid is recycle material and not theconcentrated material, the washing fluid possesses less viscosity andaids in washing down the interior walls of the primary separatingchamber. Moreover, this wash fluid having a lower temperature than thetemperature of the efl'luent gases discharged from the primaryseparating chamber, has a further effect which will be discussedhereinafter.

Turning now to Figure 4 of the drawings which is a somewhat enlargeddetail of the evaporating chamber, it will be noted that the gasesrising through duct enter into the space inside the path of rotation ofthe impeller blades 51, or stated in another way, such gases aredischarged within the swept orbital space of rotation of the blades. Aconsiderable amount of the gases after being discharged from the top ofduct 15 will be caused to change their direction from vertical toapproximately horizontal and will pass outwardly through the spacesbetween the impeller blades and in a direction toward the outer sideedges of chamber 20. Naturally, since the impeller and its blades arerotating around a vertical axis, the gases, although travelinghorizontally, will travel in paths which are more or less curved sincethe overall effect of the impeller is to create a cyclonic effect withinchamber 20. Some of the gases, however, upon being discharged fromimpeller 51 will be caused to reverse their direction nearly F. and willbe swept downwardly under the bottom edges of the impeller blades. Thesegases perform :a beneficial effect in carrying with them particles ofsolution which will tend to bathe the top edges of duct 15 andparticularly the lips 22 so as to avoid overheating and possibledecomposition or caramelization at this point. It will also be observedthat the major course of travel of the gases being sucked upwardlythrough duct 15 is directionally opposed to the downward course oftravel of the fiuid being discharged through orifices 53d from rotatingshaft 45. The downwardly moving fluids are in efiect cushioned on therising gases and are thrown outwardly and thoroughly intermingled with.the gases even before the mixture of gases and liquid approaches theimpeller blades per so. A considerable portion of the liquid so thrownout will impinge upon the surfaces of the impeller blades and willtravel outwardly to the impeller blade edges.

The air outlet orifice 19 at the upper end of jacket 17, preferablyterminates just under annular lip 22 so that the jacket air may bedischarged into the interior of evaporating chamber 20. This smallamount of additional air discharged into chamber 20 does not materiallyalter the temperature characteristics of the main stream of hot gases;nevertheless this air will be somewhat cooler than the temperature ofthe hot gases and will serve to keep lip 22 and the adjacent surfaces ofbottom 2ll somewhat cooler than they otherwise would be. it is extremelyimportant to keep these particular metal surfaces as cool as possiblesince it is at this point so closely adjacent the inflowing stream ofhot gases that the danger of decomposition and caramelization isgreatest. To assist further the elimination of this danger, it will benoted that the impeller blades, operating slightly above bottom 21 ofchamber 20, create a small area of partial vacuum and cause a recycle ofgases backwardly and inwardly toward the axis of the rotating shaft and,of course, the axis of conduit 15. This recycle flow tends to pass thecooled gases inwardly and to bathe the surfaces of bottom 21 and lip 22with a stream of relatively cool gas, which carries some entrainedliquid which, in turn, washes the surfaces and prevents the accumulationof any sticky deposits with attendant decomposition. Arrows and symbolshave been added on Figure 4 of the drawing to show the relativedirections of desiccating gases (represented by arrows marked with a G)meeting the concurrent flow of liquids (designated as arrows marked withthe letter L) which change direction and intermingle to form a fluidmixture of liquid and gases (designated as arrows marked with the symbolGL). The blades, since they are rotating rapidly in an essentially fluidmedium, will create at the tip of each blade and immediately behind itan area of at least a partial vacuum. It is in this area that thepreponderance of the evaporation of moisture appears to take place.After the drops or droplets of fluid have passed beyond the effectivepath of the impeller blades, they are thrown outwardly against the innerwall of chamber 269 where they are permitted to drain downwardly to thebottom and thence drain outwardly through duct 23. This dischargingmovement of the liquid through duct 23 is assisted by the concurrentflow of the gases.

The efficiency and economyof this apparatus is apparent from thefollowing example of a typical commerical plant operation convertingcitrus cannery waste into valuable feed products according toapplicants, U. S. Patent Re. 22,865.

The citrus fruitcannery waste is received into the mill at an average of40,600 pounds per hour. After chemical treatment it is pressed into twoproducts, 40 percent resulting in a press cake which is dried as a dairyfeed and 60 percent, or to be exact for the present example 24,370pounds, results as a press liquid containing 8 /2 percent of dissolvedsugars, other organic solids and a suspension of fine particles of peeland pectous substances, the balance, or 91.5% being moisture. This pressliquid is charged as the feed stock to the apparatus herein describedthrough pipe 25. For simplicity in description the present invention maybe described as a first effect" system. Water is evaporated and removedin the first effect at a rate of 14,500 pounds per hour resulting in aconcentrated thin syrup of approximately 21 Brix weighing approximately9,870 pounds. This thin syrup may be pumped into a second effectconcentrating system such as described in application Serial No. 64,538,filed December 10, 1948 by Charles R. Picker, now abandoned, in whichthe latent energy carried by the saturated gases from the first effectare released to evaporate an additional 7,000 pounds of water resultingin a finished syrup of approximately 72 Brix and weighing approximately2,870 pounds. The whole evaporating operation in both first effect andsecond effect is accomplished by burning an approximate average of 87gallons of fuel oil per hour. Since this fuel oil contains about 150,000B. t. u.s per gallon there is a heat release of 13,050,000 B. t. u.s perhour. Assuming a requirement of 1,000 B. t. u.s per pound of waterevaporated, the 14,500 pounds of water. removed in the first efiect willhave been evaporated at the apparent but unbelievable thermal efiiciencyof 115 percent. Actually, the excess B. t. u.s are probably obtainedfrom the electric energy used by the motor to drive the impeller. Sincean additional 7,000 pounds of water is removed in the second effectwithout added fuel of heat fuel there will have been evaporated 21,500pounds of water equivalent to a heat input of 21,500,000 B. t. u.s on afuel release of 13,050,000 B. t. u.s or 607 B. t. u.s per pound of waterevaporated. The 2,870 pounds of molasses produced is equivalent, at 11pounds per gallon, to 260 gallons. Therefore there was used .335 gallonof fuel oil per gallon of molasses produced.

The machine is capable of continuous operation, with only seasonalcleaning, at this uniform high efficiency whereas triple effect steamevaporators in the same locality are requiring .5 to .8 gallon of fueloil per gallon of molasses produced because of boiler losses and theprogressive scaling of the evaporator tubes between every 72 hourclean-out period.

In one modification of the invention the combustion zone 4 is usuallyapproximately 3000 F., and in gas mixing chamber 9 the hot gases soproduced are blended with auxiliary outside air to reduce the gastemperature of the mixed air and furnace gas to approximately 1400 F.For such combustion, about 4,500 cubic feet per minute of air isrequired for the primary combustion, while about 5,450 cubic feet perminute of auxiliary air is added through duct 11 to form the mixed airand furnace gas. The addition of auxiliary air to the furnace gas notonly has the effect of cooling the furnace gas but also has the effectof minimizing the presence of incompeltely oxidized fuel in the furnacegases.

The mixed hot gases formed in chamber 9 are sucked upwardly and enterthe evaporating chamber at approximately 1400 F. There they meet thedown-flowing recycle liquid at a temperature of about 148 F. and themixture of liquid and hot gases undergoes a profound and efficient heatexchange. The temperatures of the liquid discharged from the impellervane rises from 148 F. to about 157 F. while the temperature of thegases in the evaporating chamber is reduced from 1400 F. to about 165 F.Moreover, the gases at this reduced temperature are nearly saturatedwith water vapor.

After being discharged through conduit 23 and 24 into the primaryseparating chamber 55, very little temperature change occurs in eitherthe gases or the liquid. The liquid thrown out of the gas stream inchamber 55 and that which drains downwardly by gravity remains at atemperature of approximately 157 F. The gas within chamber 55 remains ata temperature of approximately 165 F. However, the gas when passingthrough throat 58 and through the spray produced by sprayhead 54 has itstemperature reduced to about 157 F. and is found to be saturated withvapor; incidentally, the temperature of 157 F. is the dew-point of thegas under these conditions.

The concentrated liquid collected in basin 56 is discharged into theconcentrate vat 31 at a temperature of about 157 F. Some of thisconcentrate passes under baffle 37 and blends with liquid from thesupply vat 28 which likewise has passed under batfie 36. If desired,recycle vat 30 may be provided with an agitating propeller or somemechanical means for thoroughly mixing the concentrate liquid and thestock liquid, but it has been found that the two liquids mix readily andthat the recycle mixed liquid has a temperature of about 148 F. Therecycle liquid at this temperature is piped through pipe 40 and 41 andis at that temperature when discharged through orifices 50. Similarly,the increment of recycle liquid which is piped through pipe 42 anddischarged through nozzle 54 is at a temperature of 148 F. where it isthus able to produce a cooling effect on the efiiuent gases in throat58. After the system is on stream an average input of fresh stock is 47gallons per minute, the average rate of recycle, i. e., liquid chargedinto pipe 40, is 250 gallons per minute. Thus roughly, four parts ofconcentrated liquid is recycled with each one part of fresh stock.

In general, the process described above is carried out in a system whichis maintained under atmospheric pressure throughout. The location andarrangement of the duct 15 permits the hot gases drawn therethrough tocome into direct contact with liquids, which, while they contain largequantities of water, also contain easily decomposable materials andmaterials which possess high viscosities when not in dilute solution.Notwithstanding these properties of the materials the recycle liquidwhich is charged into the evaporating chamber at 148 F. does not haveits temperature raised much more than about 10 F., even though in directand intimate contact with gases which initially possess temperatures ashigh as 1400 F. The efficiency of the heat exchange is apparent from thefact that the liquid temperature is only raised about 10 F. while thegas temperature is reduced from 1400 F. to approximately 165 F, yet thecooled gases are not completely saturated. Moreover, the liquid, sinceit is meeting a gas stream which is flowing at a rate of approximately10,000 feet per minute, is first forced into intimate contact with theheating gases, then into a zone of at least partial vacuum, andn thencequickly thrown into a relatively cool zone where chances ofdecomposition or caramelization are virtually eliminated.

The foregoing example illustrates the process with relation to citruspressed liquors. The process may be employed with the so-called wasteliquor, or fish stick obtained from the menhaden and related fishprocessing industries. The temperature of the liquid and the temperatureof the exhaust gases discharged from the evaporating chamber and intothe primary separating zone vary slightly depending upon the kind ofliquid being evaporated and the solid content of the liquid. Thus in theexample with citrus press liquors, the exhaust gases-are at atemperature of about 165 F. while the concentrated liquid is at atemperature of about 157 F. With pure water, having no solid content,the exhaust gas temperature would be 159 F. and the temperature ofunevaporated water would be 157 F. With the fish stick or fish pressingwaters containing initially about percent to 6 percent dissolved solids,the liquid temperature of the liquid collected in basin 56 will beapproximately 155 F. while the gas temperature will be approximately 170F.

It has been found desirable to utilize the present system, inconcentrating materials of the nature described, down to around to 22Brix or to a solid content of about 20 percent to 22 percent. Theconcentration, however, may be carried out to a greater degree in thissystern even up to products having percent solid content as anintermediate thin syrup product. With this higher concentration it willbe found that the relative temperature of the liquid concentrate, willbe about 162 F., while the relative gas temperature will vary between165 F. and 170 F. For most materials and under most efiicientoperations, the general spread between the discharge concentrate liquidtemperature and the effluent gas temperature is about 8 F.

Depending upon the nature of the material being concentrated and inspite of the use of the sprayhead 54, some small amount of concentrateand certain amounts of condensed water will be found to exist in chamber60. Consequently, this chamber is utilized as a secondary separatingzone. Liquids are permitted to flow down the sides of the chamber andcollect in basin 63 so that the gases finally discharged through duct 61are substantially purged of entrained solution. These discharge gases,however, contain appreciable heat both sensible and latent and aregenerally substantially saturated with water vapor. Therefore, they arecapable of performing further useful work. In general, the liquidscollected in basin 63 are somewhat more diluted with water than is thedesired concentrate. Consequently, it is preferred to convey suchliquids from pipe 64 and to introduce them into the supply vat 23 foradmixture with fresh stock.

It will be understood that certain variations in the foregoing processmay be employed. Thus, while the temperature of 1400 F. has been givenas a desirable temperature for the heating gases introduced into theevaporating chamber from duct 15, temperatures somewhat lower, such as800 F. to 1300 F., may be employed and temperatures somewhat higher,such as 1600 F. to 1900 F. may be employed.

Where my process and apparatus are employed to pro duce a partiallyconcentrated product, i. e., a thin syrup, the temperature of theheating gases may fall within a broad range of about 800 F. to 1900 F. Amore specific range of between about 1200 F. and about 1600 F. ispreferred since the evaporating process may then be more economicallypracticed and with the least wear on the equipment. However, whereevaporation with extreme rapidity is desired, heating gases attemperatures of 2000 F. or somewhat higher may be employed and where thepresent apparatus is utilized to make a product of high concentration,even up to 84 Brix, gas temperatures below 800 F. may be employed. Insuch operations the temperature of the concentrate should be controlledso as not to exceed say 120 F. Such extreme operations, while feasible,are at the expense of fuel and operating efficiency which characterizesthe preferred operating conditions.

It will be understood that the temperature of the exhaust gases and ofthe separated concentrate dependv somewhat upon the nature of the solidsbeing concentrated. Some of the solids, by virtue of viscosity and whatmight be termed water-compatibility resist concentration i. e. retainwater with stubborn tenacity. Where this condition exists the spreadbetween the exhaust gas temperature and the temperature of theconcentrate, tends to increase. In particularly stubborn solutions thistemperature spread may be as high as 15 F. although as mentioned abovethe desired average is about 8 F.

Where higher or lower than 1400 F. temperatures are 10 employed,consideration should be given to the recycle ratio of mixed concentrateand fresh feed stock. In general, the higher the temperature of theheating gases, the greater the proportion of relatively dilute feedstock in the recycle stock. This leaner ratio will provide more water tobe evaporated and the cooling eifect of the evaporation of thisadditional water will compensate for a higher temperature of the heatinggases. Conversely, with heating gases at a temperature of below 1400"F., a somewhat higher ratio of concentrate to feed stock will in generalbe employed. It is preferred to operate at a heating gas temperature ofabout 1400 F. and with recycle stock formed in the ratio of one part offresh feed for each four parts of concentrate. This ratio, however, mayvary between one to two and one to ten depending upon the nature of thesolution being concentrated, the nature of the materials in thesolution, and the degree of concentration desired in the final product,as well as of course, the temperature of the heating gases.

The foregoing described apparatus and process possesses very distinctadvantages not found in prior art. It is possible to concentratematerials without decomposition, charring, or caramelization or stickingto the Walls of the apparatus which in prior art systems invariablyoccurs at points in the apparatus when overheated. It should beremembered that the materials which are successfully concentrated by thepresent invention are extremely difficult to handle. This difficulty isin part due to the characteristic of forming solutions of progressivelyhigher viscosity as water is being removed from the solution. Prior artefforts to carry out the desired concentration have required expensiveequipment, constant personal supervision, and generally agitation of theheated body of liquid so as to avoid the decomposition of the product.The present invention is carried out con tinuously, requires littlepersonal supervision, and at no stage of the apparatus or process isthere any point where overheating causes charting, decomposition, orcaramelization. Another very important factor is that while the etfectof vacuum heating occurs in a limited zone in the evaporating chamber,the system is nevertheless entirely an atmospheric system. Consequently,the expensive equipment and expensive controls required for prior artvacuum heating systems is entirely eliminated.

While a preferred embodiment of the invention has been disclosed, it isto be understood that this disclosure is for the purpose of illustrationand that various changes and modifications may be made without departingfrom the spirit and scope of the invention as set forth in the appendedclaims.

I claim:

1. A continuous process of removing moisture from solutions andsuspensions of materials which form syrupy, gel-like, viscous fluidswhen concentrated which comprises the steps of passing a stream ofhighly heated combustion gases at high velocity and at atmosphericpressure into an evaporating zone, passing a stream of liquid into saidevaporating zone along an axis common to the two streams, countercurrentto said gas stream, and in such manner as to impinge upon the gas streamso as to produce a state of turbulence, forming a single, resultantconcurrent stream of the gases, vapors and finely divided liquidparticles in turbulent, intimate contact, moving the so-formed resultantlinear stream away at substantially right angles to the axis ofimpingement to a separately enclosed separating zone of quiescenceremote from the evaporating zone and withdrawing from said separatingzone, cooled, vapor-laden exhaust gas.

2. The process of claim 1 wherein a small amount of the liquid iswithdrawn from the stream to he evaporated and intimately contacted withthe gases in the separating zone to remove entrained liquid particles.

3. The process of claim 1 wherein a portion of the concentrated liquidis blended with the feed. stock liquid 11 and recycled to theevaporating zone while an additional portion of the concentrate iswithdrawn as product.

4. The process of claim 1 wherein an additional supply of cooler gas issupplied in an annular stream about the stream of hot gases.

5. A continuous process of removing moisture from solutions andsuspensions of materials which form syrupy, gellike, viscous fluids whenconcentrated which comprises the steps of passing a stream of highlyheated combustion gases at high velocity and at atmospheric pressureupwardly into an evaporating zone, passing a stream of feed stockcomprising warm liquid downwardly into said evaporating zone, saidstreams of gas and liquid having a common axis, to form an inner zone ofturbulence within said evaporating zone, bringing said stream ofcombustion gases and said stream of Warm liquid into intimate,heat-exchange, and direction-changing relationship in said evaporatingzone and then passing the components of said streams through said zoneof turbulence to produce a mixture of warmer concentrated liquid andcooler exhaust gases, passing said mixture into a separate and remoteprimary separating zone, entirely removed from the influence of theturbulent mixture, and there separating and withdrawing exhaust andconcentrated liquid from said primary separating zone, conveying saidwithdrawn concentrated liquid to a collecting zone, withdrawing portionsof said concentrated liquid from said collecting zone, blending saidwithdrawn portions with fresh feed stock and conveying said blendedliquid to said evaporating zone as feed stock.

6. A continuous process of removing moisture from solutions andsuspensions of materials which form syrupy, gel-like, viscou fluids whenconcentrated which comprises the steps of passing a stream of hotcombustion gases at high velocity, at atmospheric pressure and attemperatures between about 800 F. and about 1900 F. upwardly into anevaporating zone, passing a stream of liquid at temperatures betweenabout 148 F. and about 158 F. downwardly into said evaporating zone, toform an inner zone of turbulence within said evaporating zone, bringingsaid stream of liquid and said stream of combustion gases into direct,intimate, heat-exchange and direction-changing relationship in saidevaporating zone and then passing the components of said streams throughsaid zone of turbulence to produce a mixture of concentrated liquiddroplets at a temperature of between about 157 F. and about 162 F. andexhaust gases having a temperature of between about 160 F. to about 170F., passing said mixture at said temperatures into a separate and remoteprimary separating zone, entirely removed from the influence of theturbulent mixture, there separating said exhaust gases from said liquidand separately withdrawing concentrated liquid at a temperature betweenabout 157 F. and about 162 F.

7. A continuous process of removing moisture from solutions andsuspensions of materials which form syrupy, gel-like, viscous fluidswhen concentrated which comprises the steps of passing a stream of hotcombustion gases at high velocity, at atmospheric pressure and attemperatures between about 1200" F. and about 1600 F. upwardly into anevaporating zone, passing a stream of liquid at temperatures betweenabout 148 F. and about 158 F. downwardly into said evaporating zone, toform an inner zone of turbulence within said evaporating zone, bringingsaid stream of liquid and said stream of combustion gases into direct,intimate, heatexchange and direction-changing relationship in saidevaporating zone and then passing the components of said stream throughsaid zone of turbulence to produce a mixture of concentrated liquiddroplets at a temperature of between about 157 F. and about 162 F. andexhaust gases having a temperature of between about 160 F. to about 170F., passing said mixture at said temperatures into a separate and remoteprimary separating zone, entirely removed from the influence of the:turbulent mixture, there separating said exhaust gases from said liquidand separately withdrawing concentrated liquid at a temperature betweenabout 157 F. and about 162 F, conveying said withdrawn concentratedliquid to a collecting zone, withdrawing portions of said concentratedliquid from said collecting zone while at a temperature between about157 F. and about 162 F., blending said withdrawn portions with freshfeed stock at room temperature and conveying said cooled, blended liquidto said evaporating zone.

8. A continuous process of removing moisture from solutions andsuspensions of materials which form syrupy, gel-like, viscous fluidswhen concentrated which comprises the steps of passing a stream of hotcombustion gases at high velocity, under induced pressure and at atemperature of about 1400 F., upwardly into an evaporating zone, passinga stream of liquid at a temperature of about 148 F. downwardly into saidevaporating zone, to form an inner zone of turbulence within and indirect contact with said evaporating zone, bringing said stream ofliquid and said stream of combustion gases into direct, intimate,heat-exchange, and concurrent relationship within said evaporating Zoneand then passing the components of said streams through said zone ofturbulence to produce a mixture of concentrated liquid droplets at atemperature of about 157 F. and exhaust gases at a temperature of about165 F., passing said mixture at said tempera tures into a separate andremote primary separating zone, entirely removed from the influence ofthe turbulent mixture, there separating said exhaust gases from saidliquid and withdrawing said separated liquid at a temperature of about157 F.

9. A continuous process of removing moisture from solutions andsuspensions of materials which form syrupy, gel-like, viscous fluidswhen concentrated which comprises the steps of passing a stream of hotcombustion gases at high velocity, at atmospheric pressure and at atemperature of about 1400 F. upwardly into an evaporating zone, passinga stream of liquid at a temperature of about 148 F. downwardly into saidevaporating zone, to form an inner zone of turbulence within and indirect contact with said evaporating zone thereby bringing said streamof liquid and said stream of combustion gases into direct, intimate,heat-exchange, and direction-changing relationship Within saidevaporating zone to produce a mixture of concentrated liquid droplets ata temperature of about 157 F. and exhaust gases at a temperature ofabout 165 F., passing said mixture at said temperatures into a primaryseparating zone, separating said exhaust gases from said liquid andwithdrawing said separated liquid at a temperature of about 157 F.,conveying said withdrawn liquid to a blending zone and blending part ofsaid withdrawn concentrated liquid at about 157 F. with fresh feed stockat room temperature to produce a blended recycle stock at about 148 F.,charging part of said recycle stock to said evaporating zone andconveying another part of said recycle stock to said separating zone,washing exhaust gases discharged from said separating zone with saidother part of recycle stock to reduce the temperature of the exhaustgases to about 157 F.

10. A continuous process of removing moisture from solutions andsuspensions of materials which form syrupy, gel-like, viscous fluidswhen concentrated which comprises the steps of passing a stream of hotcombustion gases at high velocity, at atmospheric pressure and at atemperature of about 1400 F. upwardly into an evaporating zone, passinga stream of liquid at a temperature of about 148 F. downwardly into saidevaporating zone, to form an inner zone of turbulence within and indirect contact with said evaporating Zone thereby bringing said streamof liquid and said stream of combustion gases into direct, intimate,heat-exchange, and direction-changing relationship within saidevaporating zone to produce a mixture of concentrated liquid droplets ata temperature of about 157 F. and exhaust gases at a temperature ofabout 165 F., passing said mixture at said temperatures into a primaryseparating zone, separating said exhaust gases from said liquid andwithdrawing said separated liquid at a temperature of about 157 F.,conveying said withdrawn liquid to a blending zone and blending part ofsaid withdrawn concentrated liquid at about 157 F. with fresh feed stockat room temperature to produce a blended stock at about 148 F. andemploying such blended stock as the feed liquid.

11. A process for producing a fluid concentrate from dilute solutionsand suspensions which comprises: generating within an enclosed space afluid flow from a vertically arranged central zone to an annular outerzone, thereby causing the entry of a stream of hot gas from outside theenclosed space, along the axis of the central zone; delivering a streamof dilute solution to the central zone in an axial directioncounter-current to the gas stream to be broken up by the kinetic forceof the gas stream into liquid droplets, thereby to form an intimatemixture of gas and liquid for rapid heat transfer, delivering suchmixture by said flow to said annular zone for continued interchange ofheat between said gas and liquid and transferring the mixture from atangential portion of the annular zone to a remote separately enclosedzone of relative quiescence to permit the gas and vapor from the liquidto separate from the unvaporized, concentrated liquid.

12. The process of claim 11 wherein a portion of the concentrated liquidis admixed With the raw feed for delivery to the initial hot centralconcentrating zone.

1.3. The process of claim 12 wherein another portion of the admixed feedand concentrate is intimately contacted with the mixture of liquid andvapor laden gas in the zone of quiescence to entrap fine liquidparticles.

References Cited in the file of this patent UNITED STATES PATENTS

1. A CONTINUOUS PROCESS OF REMOVING MOISTURE FROM SOLUTIONS ANDSUSPENSIONS OF MATERIAL WHICH FORM SYRUPY, GEL-LIKE, VISCOUS FLUIDS WHENCONCENTRATED WHICH COMPRISES THE STEPS OF PASSING A STREAM OF HIGHLYHEATED COMBUSTION GASES AT HIGH VELOCITY AND AT ATMOSPHERIC PRESSUREINTO AN EVAPORATING ZONE, PASSING A STREAM OF LIQUID INTO SAIDEVAPORATING ZONE ALONG AN AXIS COMMON TO THE TWO STREAMS, COUNTERCURRENTTO SAID GAS STREAM, AND IN SUCH MANNER AS TO IMPINGE UPON THE GAS STREAMSO AS TO PRODUCE A STATE OF TURBULENCE, FORMING A SINGLE, RE-